524.2-1

METHOD 524.2. MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY

 CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY

Revision 4.1

Edited by J.W. Munch (1995)

A. Alford-Stevens, J.W. Eichelberger, W.L. Budde - Method 524, Rev. 1.0 (1983)

R.W. Slater, Jr. - Revision 2.0 (1986)

J.W. Eichelberger, and W.L. Budde - Revision 3.0 (1989)

J.W. Eichelberger, J.W. Munch, and T.A. Bellar - Revision 4.0 (1992)

NATIONAL EXPOSURE RESEARCH LABORATORY

OFFICE OF RESEARCH AND DEVELOPMENT

U.S. ENVIRONMENTAL PROTECTION AGENCY

CINCINNATI, OHIO 45268
524.2-2

METHOD 524.2

MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY

CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY

1. SCOPE AND APPLICATION

1.1 This is a general purpose method for the identification and simultaneous measurement

of purgeable volatile organic compounds in surface water, ground water, and drinking

water in any stage of treatment (1,2). The method is applicable to a wide range of

organic compounds, including the four trihalomethane disinfection by-products, that

have sufficiently high volatility and low water solubility to be removed from water

samples with purge and trap procedures. The following compounds can be determined

by this method.

 Chemical Abstract Service

 Analyte Registry Number 

Acetone* 67-64-1

Acrylonitrile* 107-13-1

Allyl chloride* 107-05-1

Benzene 71-43-2

Bromobenzene 108-86-1

Bromochloromethane 74-97-5

Bromodichloromethane 75-27-4

Bromoform 75-25-2

Bromomethane 74-83-9

2-Butanone* 78-93-3

n-Butylbenzene 104-51-8

sec-Butylbenzene 135-98-8

tert-Butylbenzene 98-06-6

Carbon disulfide* 75-15-0

Carbon tetrachloride 56-23-5

Chloroacetonitrile* 107-14-2

Chlorobenzene 108-90-7

1-Chlorobutane* 109-69-3

Chloroethane 75-00-3

Chloroform 67-66-3

Chloromethane 74-87-3

2-Chlorotoluene 95-49-8

4-Chlorotoluene 106-43-4

Dibromochloromethane 124-48-1

1,2-Dibromo-3-chloropropane 96-12-8

1,2-Dibromoethane 106-93-4

Dibromomethane 74-95-3

1,2-Dichlorobenzene 95-50-1

1,3-Dichlorobenzene 541-73-1

1,4-Dichlorobenzene 106-46-7

trans-1,4-Dichloro-2-butene* 110-57-6

Dichlorodifluoromethane 75-71-8
524.2-3

1,1-Dichloroethane 75-34-3

1,2-Dichloroethane 107-06-2

1,1-Dichloroethene 75-35-4

cis-1,2-Dichloroethene 156-59-2

trans-1,2-Dichloroethene 156-60-5

1,2-Dichloropropane 78-87-5

1,3-Dichloropropane 142-28-9

2,2-Dichloropropane 590-20-7

1,1-Dichloropropene 563-58-6

1,1-Dichloropropanone* 513-88-2

cis-1,3-Dichloropropene 10061-01-5

trans-1,3-Dichloropropene 10061-02-6

Diethyl ether* 60-29-7

Ethylbenzene 100-41-4

Ethyl methacrylate* 97-63-2

Hexachlorobutadiene 87-68-3

Hexachloroethane* 67-72-1

2-Hexanone* 591-78-6

Isopropylbenzene 98-82-8

4-Isopropyltoluene 99-87-6

Methacrylonitrile* 126-98-7

Methylacrylate* 96-33-3

Methylene chloride 75-09-2

Methyl iodide* 74-88-4

Methylmethacrylate* 80-62-6

4-Methyl-2-pentanone* 108-10-1

Methyl-t-butyl ether* 1634-04-4

Naphthalene 91-20-3

Nitrobenzene* 98-95-3

2-Nitropropane* 79-46-9

Pentachloroethane* 76-01-7

Propionitrile* 107-12-0

n-Propylbenzene 103-65-1

Styrene 100-42-5

1,1,1,2-Tetrachloroethane 630-20-6

1,1,2,2-Tetrachloroethane 79-34-5

Tetrachloroethene 127-18-4

Tetrahydrofuran* 109-99-9

Toluene 108-88-3

1,2,3-Trichlorobenzene 87-61-6

1,2,4-Trichlorobenzene 120-82-1

1,1,1-Trichloroethane 71-55-6

1,1,2-Trichloroethane 79-00-5

Trichloroethene 79-01-6

Trichlorofluoromethane 75-69-4

1,2,3-Trichloropropane 96-18-4

1,2,4-Trimethylbenzene 95-63-6

1,3,5-Trimethylbenzene 108-67-8

Vinyl chloride 75-01-4

o-Xylene 95-47-6
524.2-4

m-Xylene 108-38-3

p-Xylene 106-42-3

* New Compound in Revision 4.0

1.2 Method detection limits (MDLs) (3) are compound, instrument and especially matrix

dependent and vary from approximately 0.02 to 1.6 :g/L. The applicable

concentration range of this method is primarily column and matrix dependent, and is

approximately 0.02 to 200 :g/L when a wide-bore thick-film capillary column is used. 

Narrow-bore thin-film columns may have a capacity which limits the range to about

0.02 to 20 :g/L. Volatile water soluble, polar compounds which have relatively low

purging efficiencies can be determined using this method. Such compounds may be

more susceptible to matrix effects, and the quality of the data may be adversely

influenced.

 

1.3 Analytes that are not separated chromatographically, but which have different mass

spectra and noninterfering quantitation ions (Table 1), can be identified and measured

in the same calibration mixture or water sample as long as their concentrations are

somewhat similar (Sect. 11.6.2). Analytes that have very similar mass spectra cannot

be individually identified and measured in the same calibration mixture or water sample

unless they have different retention times (Sect. 11.6.3). Coeluting compounds with

very similar mass spectra, typically many structural isomers, must be reported as an

isomeric group or pair. Two of the three isomeric xylenes and two of the three

dichlorobenzenes are examples of structural isomers that may not be resolved on the

capillary column, and if not, must be reported as isomeric pairs. The more water

soluble compounds (> 2% solubility) and compounds with boiling points above 200°C

are purged from the water matrix with lower efficiencies. These analytes may be more

susceptible to matrix effects.

2. SUMMARY OF METHOD

2.1 Volatile organic compounds and surrogates with low water solubility are extracted

(purged) from the sample matrix by bubbling an inert gas through the aqueous sample. 

Purged sample components are trapped in a tube containing suitable sorbent materials. 

When purging is complete, the sorbent tube is heated and backflushed with helium to

desorb the trapped sample components into a capillary gas chromatography (GC)

column interfaced to a mass spectrometer (MS). The column is temperature

programmed to facilitate the separation of the method analytes which are then

detected with the MS. Compounds eluting from the GC column are identified by

comparing their measured mass spectra and retention times to reference spectra and

retention times in a data base. Reference spectra and retention times for analytes are

obtained by the measurement of calibration standards under the same conditions used

for samples. Analytes are quantitated using procedural standard calibration (Sect.

3.14). The concentration of each identified component is measured by relating the MS

response of the quantitation ion produced by that compound to the MS response of the

quantitation ion produced by a compound that is used as an internal standard. 

Surrogate analytes, whose concentrations are known in every sample, are measured

with the same internal standard calibration procedure.
524.2-5

3. DEFINITIONS

3.1 INTERNAL STANDARD (IS) -- A pure analyte(s) added to a sample, extract, or

standard solution in known amount(s) and used to measure the relative responses of

other method analytes and surrogates that are components of the same sample or

solution. The internal standard must be an analyte that is not a sample component.

3.2 SURROGATE ANALYTE (SA) -- A pure analyte(s), which is extremely unlikely to be

found in any sample, and which is added to a sample aliquot in known amount(s)

before extraction or other processing and is measured with the same procedures used

to measure other sample components. The purpose of the SA is to monitor method

performance with each sample.

3.3 LABORATORY DUPLICATES (LD1 and LD2) -- Two aliquots of the same sample taken

in the laboratory and analyzed separately with identical procedures. Analyses of LD1

and LD2 indicates precision associated with laboratory procedures, but not with

sample collection, preservation, or storage procedures.

3.4 FIELD DUPLICATES (FD1 and FD2) -- Two separate samples collected at the same

time and place under identical circumstances and treated exactly the same throughout

field and laboratory procedures. Analyses of FD1 and FD2 give a measure of the

precision associated with sample collection, preservation and storage, as well as with

laboratory procedures.

3.5 LABORATORY REAGENT BLANK (LRB) -- An aliquot of reagent water or other blank

matrix that is treated exactly as a sample including exposure to all glassware,

equipment, solvents, reagents, internal standards, and surrogates that are used with

other samples. The LRB is used to determine if method analytes or other interferences

are present in the laboratory environment, the reagents, or the apparatus.

3.6 FIELD REAGENT BLANK (FRB) -- An aliquot of reagent water or other blank matrix

that is placed in a sample container in the laboratory and treated as a sample in all

respects, including shipment to the sampling site, exposure to sampling site conditions,

storage, preservation, and all analytical procedures. The purpose of the FRB is to

determine if method analytes or other interferences are present in the field

environment.

3.7 LABORATORY PERFORMANCE CHECK SOLUTION (LPC) -- A solution of one or more

compounds (analytes, surrogates, internal standard, or other test compounds) used to

evaluate the performance of the instrument system with respect to a defined set of

method criteria.

3.8 LABORATORY FORTIFIED BLANK (LFB) -- An aliquot of reagent water or other blank

matrix to which known quantities of the method analytes are added in the laboratory. 

The LFB is analyzed exactly like a sample, and its purpose is to determine whether the

methodology is in control, and whether the laboratory is capable of making accurate

and precise measurements.

3.9 LABORATORY FORTIFIED SAMPLE MATRIX (LFM) -- An aliquot of an environmental

sample to which known quantities of the method analytes are added in the laboratory. 
524.2-6

The LFM is analyzed exactly like a sample, and its purpose is to determine whether the

sample matrix contributes bias to the analytical results. The background

concentrations of the analytes in the sample matrix must be determined in a separate

aliquot and the measured values in the LFM corrected for background concentrations.

3.10 STOCK STANDARD SOLUTION (SSS) -- A concentrated solution containing one or

more method analytes prepared in the laboratory using assayed reference materials or

purchased from a reputable commercial source.

 3.11 PRIMARY DILUTION STANDARD SOLUTION (PDS) -- A solution of several analytes

prepared in the laboratory from stock standard solutions and diluted as needed to

prepare calibration solutions and other needed analyte solutions.

 3.12 CALIBRATION STANDARD (CAL) -- A solution prepared from the primary dilution

standard solution or stock standard solutions and the internal standards and surrogate

analytes. The CAL solutions are used to calibrate the instrument response with respect

to analyte concentration.

3.13 QUALITY CONTROL SAMPLE (QCS) -- A solution of method analytes of known

concentrations which is used to fortify an aliquot of LRB or sample matrix. The QCS is

obtained from a source external to the laboratory and different from the source of

calibration standards. It is used to check laboratory performance with externally

prepared test materials.

3.14 PROCEDURAL STANDARD CALIBRATION -- A calibration method where aqueous

calibration standards are prepared and processed (e.g. purged,extracted, and/or

derivatized) in exactly the same manner as a sample. All steps in the process from

addition of sampling preservatives through instrumental analyses are included in the

calibration. Using procedural standard calibration compensates for any inefficiencies in

the processing procedure.

4. INTERFERENCES

4.1 During analysis, major contaminant sources are volatile materials in the laboratory and

impurities in the inert purging gas and in the sorbent trap. The use of Teflon tubing,

Teflon thread sealants, or flow controllers with rubber components in the purging

device should be avoided since such materials out-gas organic compounds which will

be concentrated in the trap during the purge operation. Analyses of laboratory reagent

blanks provide information about the presence of contaminants. When potential

interfering peaks are noted in laboratory reagent blanks, the analyst should change the

purge gas source and regenerate the molecular sieve purge gas filter. Subtracting blank

values from sample results is not permitted.

4.2 Interfering contamination may occur when a sample containing low concentrations

of volatile organic compounds is analyzed immediately after a sample containing

relatively high concentrations of volatile organic compounds. A preventive technique is

between-sample rinsing of the purging apparatus and sample syringes with two

portions of reagent water. After analysis of a sample containing high concentrations of

volatile organic compounds, one or more laboratory reagent blanks should be analyzed

to check for cross-contamination.
524.2-7

4.3 Special precautions must be taken to determine methylene chloride. The analytical

and sample storage area should be isolated from all atmospheric sources of methylene

chloride, otherwise random background levels will result. Since methylene chloride will

permeate Teflon tubing, all GC carrier gas lines and purge gas plumbing should be

constructed of stainless steel or copper tubing. Laboratory worker's clothing should be

cleaned frequently since clothing previously exposed to methylene chloride fumes

during common liquid/liquid extraction procedures can contribute to sample contamination.

4.4 Traces of ketones, methylene chloride, and some other organic solvents can be present

even in the highest purity methanol. This is another potential source of contamination,

and should be assessed before standards are prepared in the methanol.

5. SAFETY

5.1 The toxicity or carcinogenicity of chemicals used in this method has not been precisely

defined; each chemical should be treated as a potential health hazard, and exposure to

these chemicals should be minimized. Each laboratory is responsible for maintaining

awareness of OSHA regulations regarding safe handling of chemicals used in this

method. Additional references to laboratory safety are available (4-6) for the

information of the analyst.

5.2 The following method analytes have been tentatively classified as known or suspected

human or mammalian carcinogens: benzene, carbon tetrachloride,

1,4-dichlorobenzene, 1,2-dichlorethane, hexachlorobutadiene,

1,1,2,2-tetrachloroethane, 1,1,2-trichloroethane, chloroform,

1,2-dibromoethane,tetrachloroethene, trichloroethene, and vinyl chloride. Pure

standard materials and stock standard solutions of these compounds should be

handled in a hood. A NIOSH/MESA approved toxic gas respirator should be worn when

the analyst handles high concentrations of these toxic compounds.

6. EQUIPMENT AND SUPPLIES (All specifications are suggested. Catalog numbers are

included for illustration only.)

6.1 SAMPLE CONTAINERS -- 40-mL to 120-mL screw cap vials each equipped with a

Teflon faced silicone septum. Prior to use, wash vials and septa with detergent and

rinse with tap and distilled water. Allow the vials and septa to air dry at room

temperature, place in a 105o

C oven for 1 hr, then remove and allow to cool in an area

known to be free of organics.

6.2 PURGE AND TRAP SYSTEM -- The purge and trap system consists of three separate

pieces of equipment: purging device, trap, and desorber. Systems are commercially

available from several sources that meet all of the following specifications.

6.2.1 The all glass purging device (Figure 1) should be designed to accept 25-mL

samples with a water column at least 5 cm deep. A smaller (5-mL) purging

device is recommended if the GC/MS system has adequate sensitivity to

obtain the method detection limits required. Gaseous volumes above the

sample must be kept to a minimum (< 15 mL) to eliminate dead volume

effects. A glass frit should be installed at the base of the sample chamber so
524.2-8

the purge gas passes through the water column as finely divided bubbles with

a diameter of < 3 mm at the origin. Needle spargers may be used, however,

the purge gas must be introduced at a point about 5 mm from the base of the

water column. The use of a moisture control device is recommended to

prohibit much of the trapped water vapor from entering the GC/MS and

eventually causing instrumental problems.

6.2.2 The trap (Figure 2) must be at least 25 cm long and have an inside diameter

of at least 0.105 in. Starting from the inlet, the trap should contain 1.0 cm of

methyl silicone coated packing and the following amounts of adsorbents: 1/3

of 2,6-diphenylene oxide polymer, 1/3 of silica gel, and 1/3 of coconut

charcoal. If it is not necessary to determine dichlorodifluoromethane, the

charcoal can be eliminated and the polymer increased to fill 2/3 of the trap. 

Before initial use, the trap should be conditioned overnight at 180o

C by

backflushing with an inert gas flow of at least 20 mL/min. Vent the trap

effluent to the room, not to the analytical column. Prior to daily use, the trap

should be conditioned for 10 min at 180o

C with backflushing. The trap may

be vented to the analytical column during daily conditioning; however, the

column must be run through the temperature program prior to analysis of

samples. The use of alternative sorbents is acceptable provided the data

acquired meets all quality control criteria described in Section 9, and provided

the purge and desorption procedures specified in Section 11 of the method

are not changed. Specifically, the purging time, the purge gas flow rate, and

the desorption time may not be changed. Since many of the potential

alternate sorbents may be thermally stable above 180°C, alternate traps may

be desorbed and baked out at higher temperatures than those described in

Section 11. If higher temperatures are used, the analyst should monitor the

data for possible analyte and/or trap decomposition.

6.2.3 The use of the methyl silicone coated packing is recommended, but not

mandatory. The packing serves a dual purpose of protecting the Tenax

adsorbant from aerosols, and also of insuring that the Tenax is fully enclosed

within the heated zone of the trap thus eliminating potential cold spots. 

Alternatively, silanized glass wool may be used as a spacer at the trap inlet.

6.2.4 The desorber (Figure 2) must be capable of rapidly heating the trap to 180o

C

either prior to or at the beginning of the flow of desorption gas. The polymer

section of the trap should not be heated higher than 200o

C or the life

expectancy of the trap will decrease. Trap failure is characterized by a

pressure drop in excess of 3 lb/in2

 across the trap during purging or by poor

bromoform sensitivities. The desorber design illustrated in Fig. 2 meets these

criteria.

6.3 GAS CHROMATOGRAPHY/MASS SPECTROMETER/DATA SYSTEM (GC/MS/DS)

6.3.1 The GC must be capable of temperature programming and should be

equipped with variable-constant differential flow controllers so that the column

flow rate will remain constant throughout desorption and temperature program

operation. If the column oven is to be cooled to 10o

C or lower, a subambient

oven controller will likely be required. If syringe injections of 4-
524.2-9

bromofluorobenzene (BFB) will be used, a split/splitless injection port is

required.

6.3.2 Capillary GC Columns. Any gas chromatography column that meets the

performance specifications of this method may be used (Sect. 10.2.4.1). 

Separations of the calibration mixture must be equivalent or better than those

described in this method. Four useful columns have been evaluated, and

observed compound retention times for these columns are listed in Table 2.

6.3.2.1 Column 1 -- 60 m x 0.75 mm ID VOCOL (Supelco, Inc.) glass

wide-bore capillary with a 1.5 :m film thickness.

Column 2 -- 30 m x 0.53 mm ID DB-624 (J&W Scien-tific, Inc.)

fused silica capillary with a 3 :m film thickness.

Column 3 -- 30 m x 0.32 mm ID DB-5 (J&W Scientific, Inc.)

fused silica capillary with a 1 :m film thickness.

Column 4 -- 75 m x 0.53 mm id DB-624 (J&W Scien-tific, Inc.)

fused silica capillary with a 3 :m film thickness.

6.3.3 Interfaces between the GC and MS. The interface used depends on the

column selected and the gas flow rate. 

6.3.3.1 The wide-bore columns 1, 2, and 4 have the capacity to accept

the standard gas flows from the trap during thermal desorption,

and chromatography can begin with the onset of thermal

desorption. Depending on the pumping capacity of the MS, an

additional interface between the end of the column and the MS

may be required. An open split interface (7) or an all-glass jet

separator is an acceptable interface. Any interface can be used if

the performance specifications described in this method (Sect. 9

and 10) can be achieved. The end of the transfer line after the

interface, or the end of the analytical column if no interface is

used, should be placed within a few mm of the MS ion source.

6.3.3.2 When narrow bore column 3 is used, a cryogenic interface placed

just in front of the column inlet is suggested. This interface condenses the desorbed sample components in a narrow band on an

uncoated fused silica precolumn using liquid nitrogen cooling. 

When all analytes have been desorbed from the trap, the interface

is rapidly heated to transfer them to the analytical column. The

end of the analytical column should be placed within a few mm of

the MS ion source. A potential problem with this interface is

blockage of the interface by frozen water from the trap. This

condition will result in a major loss in sensitivity and chromatographic resolution.

6.3.4 The mass spectrometer must be capable of electron ionization at a nominal

electron energy of 70 eV. The spectrometer must be capable of scanning from
524.2-10

35 to 260 amu with a complete scan cycle time (including scan overhead) of

2 sec or less. (Scan cycle time = Total MS data acquisition time in seconds

divided by number of scans in the chromatogram.) The spectrometer must

produce a mass spectrum that meets all criteria in Table 3 when 25 ng or less

of 4-bromofluorobenzene (BFB) is introduced into the GC. An average spectrum across the BFB GC peak may be used to test instrument performance.

6.3.5 An interfaced data system is required to acquire, store, reduce, and output

mass spectral data. The computer software should have the capability of

processing stored GC/MS data by recognizing a GC peak within any given

retention time window, comparing the mass spectra from the GC peak with

spectral data in a user-created data base, and generating a list of tentatively

identified compounds with their retention times and scan numbers. The

software must allow integration of the ion abundance of any specific ion

between specified time or scan number limits. The software should also allow

calculation of response factors as defined in Sect. 10.2.6 (or construction of a

linear or second order regression calibration curve), calculation of response

factor statistics (mean and standard deviation), and calculation of concentrations of analytes using either the calibration curve or the equation in Sect. 12.

6.4 SYRINGE AND SYRINGE VALVES

6.4.1 Two 5-mL or 25-mL glass hypodermic syringes with Luer-Lok tip (depending

on sample volume used).

6.4.2 Three 2-way syringe valves with Luer ends.

6.4.3 Micro syringes - 10, 100 :L.

6.4.4 Syringes - 0.5, 1.0, and 5-mL, gas tight with shut-off valve.

6.5 MISCELLANEOUS

6.5.1 Standard solution storage containers -- 15-mL bottles with Teflon lined screw

caps.

7. REAGENTS AND STANDARDS

 7.1 TRAP PACKING MATERIALS

7.1.1 2,6-Diphenylene oxide polymer, 60/80 mesh, chromatographic grade (Tenax

GC or equivalent).

7.1.2 Methyl silicone packing (optional) -- OV-1 (3%) on Chromosorb W, 60/80

mesh, or equivalent.

7.1.3 Silica gel -- 35/60 mesh, Davison, grade 15 or equivalent.

7.1.4 Coconut charcoal -- Prepare from Barnebey Cheney, CA-580-26 lot #M-2649

(or equivalent) by crushing through 26 mesh screen.
524.2-11

7.2 REAGENTS

7.2.1 Methanol -- Demonstrated to be free of analytes.

7.2.2 Reagent water -- Prepare reagent water by passing tap water through a filter

bed containing about 0.5 kg of activated carbon, by using a water purification

system, or by boiling distilled water for 15 min followed by a 1-h purge with

inert gas while the water temperature is held at 90o

C. Store in clean, narrow-mouth bottles with Teflon lined septa and screw caps.

7.2.3 Hydrochloric acid (1+1) -- Carefully add measured volume of conc. HCl to

equal volume of reagent water.

7.2.4 Vinyl chloride -- Certified mixtures of vinyl chloride in nitrogen and pure vinyl

chloride are available from several sources (for example, Matheson, Ideal Gas

Products, and Scott Gases).

7.2.5 Ascorbic acid -- ACS reagent grade, granular.

7.2.6 Sodium thiosulfate -- ACS reagent grade, granular.

7.3 STOCK STANDARD SOLUTIONS -- These solutions may be purchased as certified

solutions or prepared from pure standard materials using the following procedures. 

One of these solutions is required for every analyte of concern, every surrogate, and the

internal standard. A useful working concentration is about 1-5 mg/mL.

7.3.1 Place about 9.8 mL of methanol into a 10-mL ground-glass stoppered volumetric flask. Allow the flask to stand, unstoppered, for about 10 min or until

all alcohol-wetted surfaces have dried and weigh to the nearest 0.1 mg.

7.3.2 If the analyte is a liquid at room temperature, use a 100-:L syringe and

immediately add two or more drops of reference standard to the flask. Be

sure that the reference standard falls directly into the alcohol without contacting the neck of the flask. If the analyte is a gas at room temperature, fill a

5-mL valved gas-tight syringe with the standard to the 5.0-mL mark, lower

the needle to 5 mm above the methanol meniscus, and slowly inject the

standard into the neck area of the flask. The gas will rapidly dissolve in the

methanol.

7.3.3 Reweigh, dilute to volume, stopper, then mix by inverting the flask several

times. Calculate the concentration in :g/:L from the net gain in weight. 

When compound purity is certified at 96% or greater, the weight can be used

without correction to calculate the concentration of the stock standard.

7.3.4 Store stock standard solutions in 15-mL bottles equipped with Teflon lined

screw caps. Methanol solutions of acrylonitrile, methyl iodide, and methyl

acrylate are stable for only one week at 4°C. Methanol solutions prepared

from other liquid analytes are stable for at least 4 weeks when stored at 4o

C. 
524.2-12

Methanol solutions prepared from gaseous analytes are not stable for more

than 1 week when stored at < 0o

C; at room temperature, they must be

discarded after 1 day.

7.4 PRIMARY DILUTION STANDARDS -- Use stock standard solutions to prepare primary

dilution standard solutions that contain all the analytes of concern in methanol or other

suitable solvent. The primary dilution standards should be prepared at concentrations

that can be easily diluted to prepare aqueous calibration solutions that will bracket the

working concentration range. Store the primary dilution standard solutions with

minimal headspace and check frequently for signs of deterioration or evaporation,

especially just before preparing calibration solutions. Storage times described for stock

standard solutions in Sect. 7.3.4 also apply to primary dilution standard solutions.

7.5 FORTIFICATION SOLUTIONS FOR INTERNAL STANDARD AND SURROGATES 

7.5.1 A solution containing the internal standard and the surrogate compounds is

required to prepare laboratory reagent blanks (also used as a laboratory

performance check solution), and to fortify each sample. Prepare a fortification solution containing fluorobenzene (internal standard), 1,2- dichlorobenzene-d4 (surrogate), and BFB (surrogate) in methanol at concentrations of

5 :g/mL of each (any appropriate concentration is acceptable). A 5-:L

aliquot of this solution added to a 25-mL water sample volume gives concentrations of 1 :g/L of each. A 5-:L aliquot of this solution added to a 5-mL

water sample volume gives a concentration of 5 :g/L of each. Additional

internal standards and surrogate analytes are optional. Additional surrogate

compounds should be similar in physical and chemical characteristics to the

analytes of concern.

7.6 PREPARATION OF LABORATORY REAGENT BLANK (LRB) -- Fill a 25-mL (or 5-mL)

syringe with reagent water and adjust to the mark (no air bubbles). Inject an appropriate volume of the fortification solution containing the internal standard and surrogates

through the Luer Lok valve into the reagent water. Transfer the LRB to the purging

device. See Sect. 11.1.2.

 

7.7 PREPARATION OF LABORATORY FORTIFIED BLANK -- Prepare this exactly like a

calibration standard (Sect. 7.8). This is a calibration standard that is treated as a

sample.

7.8 PREPARATION OF CALIBRATION STANDARDS

7.8.1 The number of calibration solutions (CALs) needed depends on the calibration

range desired. A minimum of three CAL solutions is required to calibrate a

range of a factor of 20 in concentration. For a factor of 50, use at least four

standards, and for a factor of 100 at least five standards. One calibration

standard should contain each analyte of concern at a concentration of 2-10

times the method detection limit (Tables 4, 5, and 7) for that compound. The

other CAL standards should contain each analyte of concern at concentrations

that define the range of the method. Every CAL solution contains the internal
524.2-13

standard and the surrogate compounds at the same concentration (5 :g/L

suggested for a 5-mL sample; 1 :g/L for a 25-mL sample).

7.8.2 To prepare a calibration standard, add an appropriate volume of a primary

dilution standard containing all analytes of concern to an aliquot of acidified

(pH 2) reagent water in a volumetric flask. Also add an appropriate volume of

internal standard and surrogate compound solution from Sect. 7.5.1. Use a

microsyringe and rapidly inject the methanol solutions into the expanded area

of the filled volumetric flask. Remove the needle as quickly as possible after

injection. Mix by inverting the flask three times only. Discard the contents

contained in the neck of the flask. Aqueous standards are not stable in a

volumetric flask and should be discarded after 1 hr unless transferred to a

sample bottle and sealed immediately. Alternately, aqueous calibration

standards may be prepared in a gas tight, 5 mL or 25 mL syringe. NOTE: If

unacidified samples are being analyzed for THMs only, calibration standards

should be prepared without acid. 

8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE

8.1 SAMPLE COLLECTION AND DECHLORINATION

8.1.1 Collect all samples in duplicate. If samples, such as finished drinking water,

are suspected to contain residual chlorine, add about 25 mg of ascorbic acid

per 40 mL of sample to the sample bottle before filling. If analytes that are

gases at room temperature (such as vinyl chloride), or analytes in Table 7 are

not to be determined, sodium thiosulfate is recommended to reduce the

residual chlorine. Three milligrams of sodium thiosulfate should be added for

each 40 mL of water sample. 

NOTE: If the residual chlorine is likely to be present > 5 mg/L, a determination of the amount of the chlorine may be necessary. Diethyl-pphenylenediamine (DPD) test kits are commercially available to determine

residual chlorine in the field. Add an additional 25 mg of ascorbic acid or 3

mg of sodium thiosulfate per each 5 mg/L of residual chlorine. 

8.1.2 When sampling from a water tap, open the tap and allow the system to flush

until the water temperature has stabilized (usually about 10 min). Adjust the

flow to about 500 mL/min and collect duplicate samples containing the

desired dechlorinating agent from the flowing stream.

8.1.3 When sampling from an open body of water, partially fill a 1-quart wide-mouth bottle or 1-L beaker with sample from a representative area. Fill duplicate

sample bottles containing the desired dechlorinating agent with sample from

the larger container.

8.1.4 Fill sample bottles to overflowing, but take care not to flush out the rapidly

dissolving dechlorinating agent. No air bubbles should pass through the

sample as the bottle is filled, or be trapped in the sample when the bottle is

sealed.
524.2-14

8.2 SAMPLE PRESERVATION

8.2.1 Adjust the pH of all samples to < 2 at the time of collection, but after

dechlorination, by carefully adding two drops of 1:1 HCl for each 40 mL of

sample. Seal the sample bottles, Teflon face down, and mix for 1 min. 

Exceptions to the acidification requirement are detailed in Sections 8.2.2 and

8.2.3. NOTE: Do not mix the ascorbic acid or sodium thiosulfate with the HCl

in the sample bottle prior to sampling.

8.2.2 When sampling for THM analysis only, acidification may be omitted if sodium

thiosulfate is used to dechlorinate the sample. This exception to acidification

does not apply if ascorbic acid is used for dechlorination.

8.2.3 If a sample foams vigorously when HCl is added, discard that sample. Collect

a set of duplicate samples but do not acidify them. These samples must be

flagged as "not acidified" and must be stored at 4°C or below. These samples

must be analyzed within 24 hr of collection time if they are to be analyzed for

any compounds other than THMs.

8.2.4 The samples must be chilled to about 4o

C when collected and maintained at

that temperature until analysis. Field samples that will not be received at the

laboratory on the day of collection must be packaged for shipment with

sufficient ice to ensure that they will arrive at the laboratory with a substantial

amount of ice remaining in the cooler.

8.2 SAMPLE STORAGE

8.2.1 Store samples at # 4o

C until analysis. The sample storage area must be free

of organic solvent vapors and direct or intense light.

8.2.2 Analyze all samples within 14 days of collection. Samples not analyzed

within this period must be discarded and replaced.

8.3 FIELD REAGENT BLANKS (FRB)

8.3.1 Duplicate FRBs must be handled along with each sample set, which is

composed of the samples collected from the same general sample site at

approximately the same time. At the laboratory, fill field blank sample bottles

with reagent water and sample preservatives, seal, and ship to the sampling

site along with empty sample bottles and back to the laboratory with filled

sample bottles. Wherever a set of samples is shipped and stored, it is accompanied by appropriate blanks. FRBs must remain hermetically sealed until

analysis.

8.3.2 Use the same procedures used for samples to add ascorbic acid and HCl to

blanks (Sect. 8.1.1). The same batch of ascorbic acid and HCl should be

used for the field reagent blanks as for the field samples. 
524.2-15

9. QUALITY CONTROL

9.1 Quality control (QC) requirements are the initial demonstration of laboratory capability

followed by regular analyses of laboratory reagent blanks, field reagent blanks, and

laboratory fortified blanks. A MDL for each analyte must also be determined. Each

laboratory must maintain records to document the quality of the data generated. 

Additional quality control practices are recommended.

9.2 Initial demonstration of low system background. Before any samples are analyzed, it

must be demonstrated that a laboratory reagent blank (LRB) is reasonably free of

contamination that would prevent the determination of any analyte of concern. Sources

of background contamination are glassware, purge gas, sorbents, reagent water, and

equipment. Background contamination must be reduced to an acceptable level before

proceeding with the next section. In general, background from method analytes should

be below the method detection limit.

9.3 Initial demonstration of laboratory accuracy and precision. Analyze four to seven

replicates of a laboratory fortified blank containing each analyte of concern at a

concentration in the range of 2-5 :g/L depending upon the calibration range of the

instrumentation.

9.3.1 Prepare each replicate by adding an appropriate aliquot of a quality control

sample to reagent water. It is recommended that a QCS from a source

different than the calibration standards be used for this set of LFBs, since it

will serve as a check to verify the accuracy of the standards used to generate

the calibration curve. This is particularly useful if the laboratory is using the

method for the first time, and has no historical data base for standards. 

Prepare each replicate by adding an appropriate aliquot of a quality control

sample to reagent water. Also add the appropriate amounts of internal

standard and surrogates. If it is expected that field samples will contain a

dechlorinating agent and HCl, then add these to the LFBs in the same

amounts proscribed in Sect. 8.1.1. If only THMs are to be determined and

field samples do not contain HCl, then do not acidify LFBs. Analyze each

replicate according to the procedures described in Section 11.

9.3.2 Calculate the measured concentration of each analyte in each replicate, the

mean concentration of each analyte in all replicates, and mean accuracy (as

mean percentage of true value) for each analyte, and the precision (as relative

standard deviation, RSD) of the measurements for each analyte. 

9.3.3 Some analytes, particularly early eluting gases and late eluting higher molecular weight compounds, will be measured with less accuracy and precision

than other analytes. However, the accuracy and precision for all analytes

must fall within the limits expressed below. If these criteria are not met for an

analyte of interest, take remedial action and repeat the measurements for that

analyte until satisfactory performance is achieved. For each analyte, the

mean accuracy must be 80-120% (i.e. an accuracy of ± 20%). The preci-
524.2-16

sion of the recovery (accuracy) for each analyte must be less than twenty

percent (<20%). These criteria are different than the ± 30% response factor

criteria specified in Sect. 10.3.5. The criteria differ, because the measurements in Sect. 9.3.3 as part of the initial demonstration of capability are

meant to be more stringent than the continuing calibration measurements in

Sect. 10.3.5.

9.3.4 To determine the MDL, analyze a minimum of 7 LFBs prepared at a low

concentration. MDLs in Table 5 were calculated from samples fortified from

0.1-0.5 :g/L, which can be used as a guide, or use calibration data to

estimate a concentration for each analyte that will yield a peak with a 3-5

signal to noise response. Analyze the 7 replicates as described in Sect.11,

and on a schedule that results in the analyses being conducted over several

days. Calculate the mean accuracy and standard deviation for each analyte. 

Calculate the MDL using the equation in Sect. 13.

9.3.5 Develop and maintain a system of control charts to plot the precision and

accuracy of analyte and surrogate measurements as a function of time. 

Charting surrogate recoveries is an especially valuable activity because

surrogates are present in every sample and the analytical results will form a

significant record of data quality.

9.4 Monitor the integrated areas of the quantitation ions of the internal standards and

surrogates (Table 1) in all samples, continuing calibration checks, and blanks. These

should remain reasonably constant over time. An abrupt change may indicate a matrix

effect or an instrument problem. If a cryogenic interface is utilized, it may indicate an

inefficient transfer from the trap to the column. These samples must be reanalyzed or

a laboratory fortified duplicate sample analyzed to test for matrix effect. A more

gradual drift of more than 50% in any area is indicative of a loss in sensitivity, and the

problem must be found and corrected.

9.5 LABORATORY REAGENT BLANKS (LRB) -- With each batch of samples processed as a

group within a work shift, analyze a LRB to determine the background system contamination.

9.6 Assessing Laboratory Performance. Use the procedures and criteria in Sects. 10.3.4

and 10.3.5 to evaluate the accuracy of the measurement of the laboratory fortified

blank (LFB), which must be analyzed with each batch of samples that is processed as

a group within a work shift. If more than 20 samples are in a work shift batch, analyze

one LFB per 20 samples. Prepare the LFB with the concentration of each analyte that

was used in the Sect. 9.3.3 analysis. If the acceptable accuracy for this measurement

(±30%) is not achieved, the problem must be solved before additional samples may be

reliably analyzed. Acceptance criteria for the IS and surrogate given in Sect.10.3.4

also applies to this LFB. 

Since the calibration check sample in Sect. 10.3.5 and the LFB are made the same

way and since procedural standards are used, the sample analyzed here may also be
524.2-17

used as a calibration check in Sect. 10.3.5. Add the results of the LFB analysis to the

control charts to document data quality.

9.7 If a water sample is contaminated with an analyte, verify that it is not a sampling error

by analyzing a field reagent blank. The results of these analyses will help define

contamination resulting from field sampling, storage and transportation activities. If the

field reagent blank shows unacceptable contamination, the analyst should identify and

eliminate the contamination.

9.8 At least quarterly, replicate LFB data should be evaluated to determine the precision of

the laboratory measurements. Add these results to the ongoing control charts to

document data quality.

9.9 At least quarterly, analyze a quality control sample (QCS) from an external source. If

measured analyte concentrations are not of acceptable accuracy, check the entire

analytical procedure to locate and correct the problem source.

9.10 Sample matrix effects have not been observed when this method is used with distilled

water, reagent water, drinking water, or ground water. Therefore, analysis of a

laboratory fortified sample matrix (LFM) is not required unless the criteria in Section

9.4 are not met. If matrix effects are observed or suspected to be causing low recoveries, analyze a laboratory fortified matrix sample for that matrix. The sample results

should be flagged and the LFM results should be reported with them.

9.11 Numerous other quality control measures are incorporated into other parts of this

procedure, and serve to alert the analyst to potential problems.

10. CALIBRATION AND STANDARDIZATION

10.1 Demonstration and documentation of acceptable initial calibration is required before

any samples are analyzed. In addition, acceptable performance must be confirmed

intermittently throughout analysis of samples by performing continuing calibration

checks. These checks are required at the beginning of each work shift, but no less

than every 12 hours. Additional periodic calibration checks are good laboratory

practice. It is highly recommended that an additional calibration check be performed

at the end of any cycle of continuous instrument operation, so that each set of field

samples is bracketed by calibration check standards. NOTE: Since this method uses

procedural standards, the analysis of the laboratory fortified blank, which is required in

Sect. 9.6, may be used here as a calibration check sample.

10.2 INITIAL CALIBRATION

 10.2.1 Calibrate the mass and abundance scales of the MS with calibration compounds and procedures prescribed by the manufacturer with any modifications

necessary to meet the requirements in Sect. 10.2.2.
524.2-18

10.2.2 Introduce into the GC (either by purging a laboratory reagent blank or making

a syringe injection) 25 ng or less of BFB and acquire mass spectra for m/z

35-260 at 70 eV (nominal). Use the purging procedure and/or GC conditions

given in Sect. 11. If the spectrum does not meet all criteria in Table 3, the

MS must be returned and adjusted to meet all criteria before proceeding with

calibration. An average spectrum across the GC peak may be used to evaluate

the performance of the system.

10.2.3 Purge a medium CAL solution, (e.g., 10-20 :g/L) using the procedure given in

Sect. 11.

10.2.4 Performance criteria for calibration standards. Examine the stored GC/MS

data with the data system software. Figures 3 and 4 shown acceptable total

ion chromatograms.

10.2.4.1 GC performance. Good column performance will produce symmetrical peaks with minimum tailing for most compounds. If peaks

are unusually broad, or if there is poor resolution between peaks,

the wrong column has been selected or remedial action is probably

necessary (Sect.10.3.6).

10.2.4.2 MS sensitivity. The GC/MS/DS peak identification software should

be able to recognize a GC peak in the appropriate retention time

window for each of the compounds in calibration solution, and

make correct tentative identifications. If fewer than 99% of the

compounds are recognized, system maintenance is required. See

Sect. 10.3.6.

10.2.5 If all performance criteria are met, purge an aliquot of each of the other CAL

solutions using the same GC/MS conditions.

10.2.6 Calculate a response factor (RF) for each analyte and isomer pair for each CAL

solution using the internal standard fluorobenzene. Table 1 contains suggested quantitation ions for all compounds. This calculation is supported in

acceptable GC/MS data system software (Sect. 6.3.5), and many other

software programs. RF is a unitless number, but units used to express

quantities of analyte and internal standard must be equivalent.

 (Ax)(Qis) RF = 

 (Ais)(Qx)

where: Ax = integrated abundance of the quantitation ion 

 of the analyte.

Ais = integrated abundance of the quantitation ion 

 of the internal standard.
524.2-19

Qx = quantity of analyte purged in nanograms or 

 concentration units.

Qis = quantity of internal standard purged in ng or 

 concentration units.

10.2.6.1 For each analyte and surrogate, calculate the mean RF from

analyses of CAL solutions. Calculate the standard deviation (SD)

and the relative standard deviation (RSD) from each mean: RSD

= 100 (SD/M). If the RSD of any analyte or surrogate mean RF

exceeds 20%, either analyze additional aliquots of appropriate

CAL solutions to obtain an acceptable RSD of RFs over the entire

concentration range, or take action to improve GC/MS performance

Sect. 10.3.6). Surrogate compounds are present at the same

concentration on every sample, calibration standard, and all types

of blanks.

10.2.7 As an alternative to calculating mean response factors and applying the RSD

test, use the GC/MS data system software or other available software to

generate a linear or second order regression calibration curve, by plotting A/Ais

vs. Qx. 

10.3 CONTINUING CALIBRATION CHECK -- Verify the MS tune and initial calibration at the

beginning of each 12-hr work shift during which analyses are performed using the

following procedure. Additional periodic calibration checks are good laboratory practice. 

It is highly recommended that an additional calibration check be performed at the end

of any cycle of continuous instrument operation, so that each set of field samples is

bracketed by calibration check standards.

10.3.1 Introduce into the GC (either by purging a laboratory reagent blank or making

a syringe injection) 25 ng or less of BFB and acquire a mass spectrum that

includes data for m/z 35-260. If the spectrum does not meet all criteria

(Table 3), the MS must be returned and adjusted to meet all criteria before

proceeding with the continuing calibration check.

10.3.2 Purge a CAL solution and analyze with the same conditions used during the

initial calibration. Selection of the concentration level of the calibration check

standard should be varied so that the calibration is verified at more than one

point over the course of several days. 

10.3.3 Demonstrate acceptable performance for the criteria shown in Sect. 10.2.4.

10.3.4 Determine that the absolute areas of the quantitation ions of the internal

standard and surrogates have not decreased by more than 30% from the

areas measured in the most recent continuing calibration check, or by more

than 50% from the areas measured during initial calibration. If these areas

have decreased by more than these amounts, adjustments must be made to

restore system sensitivity. These adjustments may require cleaning of the MS
524.2-20

ion source, or other maintenance as indicated in Sect. 10.3.6, and

recalibration. Control charts are useful aids in documenting system sensitivity

changes.

10.3.5 Calculate the RF for each analyte of concern and surrogate compound from

the data measured in the continuing calibration check. The RF for each

analyte and surrogate must be within 30% of the mean value measured in the

initial calibration. Alternatively, if a linear or second order regression is used,

the concentration measured using the calibration curve must be within 30% of

the true value of the concentration in the calibration solution. If these conditions do not exist, remedial action must be taken which may require recalibration. All data from field samples obtained after the last successful

calibration check standard, should be considered suspect. After remedial

action has been taken, duplicate samples should be analyzed if they are

available.

10.3.6 Some possible remedial actions. Major maintenance such as cleaning an ion

source, cleaning quadrupole rods, etc. require returning to the initial calibration step.

10.3.6.1 Check and adjust GC and/or MS operating conditions; check the

MS resolution, and calibrate the mass scale.

10.3.6.2 Clean or replace the splitless injection liner; silanize a new injection liner. This applies only if the injection liner is an integral part

of the system.

10.3.6.3 Flush the GC column with solvent according to manufacturer's

instructions.

10.3.6.4 Break off a short portion (about 1 meter) of the column from the

end near the injector; or replace GC column. This action will

cause a slight change in retention times. Analyst may need to

redefine retention windows.

10.3.6.5 Prepare fresh CAL solutions, and repeat the initial calibration step.

10.3.6.6 Clean the MS ion source and rods (if a quadrupole).

10.3.6.7 Replace any components that allow analytes to come into contact

with hot metal surfaces.

10.3.6.8 Replace the MS electron multiplier, or any other faulty components.

10.3.6.9 Replace the trap, especially when only a few compounds fail the

criteria in Sect. 10.3.5 while the majority are determined success-
524.2-21

fully. Also check for gas leaks in the purge and trap unit as well

as the rest of the analytical system.

10.4 Optional calibration for vinyl chloride using a certified gaseous mixture of vinyl chloride

in nitrogen can be accomplished by the following steps.

10.4.1 Fill the purging device with 25.0 mL (or 5-mL) of reagent water or aqueous

calibration standard.

10.4.2 Start to purge the aqueous mixture. Inject a known volume (between 100

and 2000 :L) of the calibration gas (at room temperature) directly into the

purging device with a gas tight syringe. Slowly inject the gaseous sample

through a septum seal at the top of the purging device at 2000 :L/min. If the

injection of the standard is made through the aqueous sample inlet port, flush

the dead volume with several mL of room air or carrier gas. Inject the gaseous standard before 5 min of the 11-min purge time have elapsed.

10.4.3 Determine the aqueous equivalent concentration of vinyl chloride standard, in

:g/L, injected with one of the following equations:

5 mL samples, S = 0.51 (C)(V)

 25 mL samples, S = 0.102 (C)(V)

where S = Aqueous equivalent concentration

 of vinyl chloride standard in :g/L;

C = Concentration of gaseous standard in mg/L (v/v);

V = Volume of standard injected in mL.

11. PROCEDURE

11.1 SAMPLE INTRODUCTION AND PURGING

11.1.1 This method is designed for a 25-mL or 5-mL sample volume, but a smaller

(5 mL) sample volume is recommended if the GC/MS system has adequate

sensitivity to achieve the required method detection limits. Adjust the helium

purge gas flow rate to 40 mL/min. Attach the trap inlet to the purging device

and open the syringe valve on the purging device. 

11.1.2 Remove the plungers from two 25-mL (or 5-mL depending on sample size)

syringes and attach a closed syringe valve to each. Warm the sample to room

temperature, open the sample bottle, and carefully pour the sample into one

of the syringe barrels to just short of overflowing. Replace the syringe plunger,

invert the syringe, and compress the sample. Open the syringe valve and vent

any residual air while adjusting the sample volume to 25.0-mL (or 5-mL). To

all samples, blanks, and calibration standards, add 5-:L (or an appropriate

volume) of the fortification solution containing the internal standard and the

surrogates to the sample through the syringe valve. Close the valve. Fill the
524.2-22

second syringe in an identical manner from the same sample bottle. Reserve

this second syringe for a reanalysis if necessary.

11.1.3 Attach the sample syringe valve to the syringe valve on the purging device. Be

sure that the trap is cooler than 25o

C, then open the sample syringe valve and

inject the sample into the purging chamber. Close both valves and initiate

purging. Purge the sample for 11.0 min at ambient temperature.

11.1.4 Standards and samples must be analyzed in exactly the same manner. Room

temperature must be reasonably constant, and changes in excess of 10°F will

adversely affect the accuracy and precision of the method. 

11.2 SAMPLE DESORPTION 

11.2.1 Non-cryogenic interface -- After the 11-min purge, place the purge and trap

system in the desorb mode and preheat the trap to 180o

C without a flow of

desorption gas. Then simultaneously start the flow of desorption gas at a flow

rate suitable for the column being used (optimum desorb flow rate is 15

mL/min) for about 4 min, begin the GC temperature program, and start data

acquisition. 

11.2.2 Cryogenic interface -- After the 11-min purge, place the purge and trap system

in the desorb mode, make sure the cryogenic interface is a -150o

C or lower,

and rapidly heat the trap to 180o

C while backflushing with an inert gas at

4 mL/min for about 5 min. At the end of the 5 min desorption cycle, rapidly

heat the cryogenic trap to 250o

C, and simultaneously begin the temperature

program of the gas chromatograph, and start data acquisition. 

11.2.3 While the trapped components are being introduced into the gas chromatograph (or cryogenic interface), empty the purging device using the sample syringe

and wash the chamber with two 25-mL flushes of reagent water. After the

purging device has been emptied, leave syringe valve open to allow the purge

gas to vent through the sample introduction needle.

11.3 GAS CHROMATOGRAPHY/MASS SPECTROMETRY -- Acquire and store data over the

nominal mass range 35-260 with a total cycle time (including scan overhead time) of

2 sec or less. If water, methanol, or carbon dioxide cause a background problem, start

at 47 or 48 m/z. If ketones are to be determined, data must be acquired starting at

m/z 43. Cycle time must be adjusted to measure five or more spectra during the elution

of each GC peak. Suggested temperature programs are provided below. Alternative

temperature programs can be used.

11.3.1 Single ramp linear temperature program for wide bore column 1 and 2 with a

jet separator. Adjust the helium carrier gas flow rate to within the capacity of

the separator, or about 15 mL/min. The column temperature is reduced 10o

C

and held for 5 min from the beginning of desorption, then programmed to

160o

C at 6oC/min, and held until all components have eluted.
524.2-23

11.3.2 Multi-ramp temperature program for wide bore column 2 with the open split

interface. Adjust the helium carrier gas flow rate to about 4.6 mL/min. The

column temperature is reduced to 10o

C and held for 6 min from the beginning

of desorption, then heated to 70o

C at 10o/min, heated to 120oC at 5o/min,

heated to 180o

 at 8o/min, and held at 180o until all compounds have eluted.

11.3.3 Single ramp linear temperature program for narrow bore column 3 with a

cryogenic interface. Adjust the helium carrier gas flow rate to about 4

mL/min. The column temperature is reduced to 10°C and held for 5 min from

the beginning of vaporization from the cryogenic trap, programmed at 6°/min

for 10 min, then 15°/min for 5 min to 145°C, and held until all components

have eluted.

11.3.4 Multi-ramp temperature program for wide bore column 4 with the open split

interface. Adjust the helium carrier gas flow rate to about 7.0 mL/min. The

column temperature is - 10°C and held for 6 min. from beginning of

desorption, then heated to 100°C at 10°C/min, heated to 200°C at 5°C/min

and held at 200°C for 8 min or until all compounds of interest had eluted.

11.4 TRAP RECONDITIONING -- After desorbing the sample for 4 min, recon-dition the trap

by returning the purge and trap system to the purge mode. Wait 15 sec, then close

the syringe valve on the purging device to begin gas flow through the trap. Maintain

the trap temperature at 180o

C. Maintain the moisture control module, if utilized, at

90°C to remove residual water. After approximately 7 min, turn off the trap heater and

open the syringe valve to stop the gas flow through the trap. When the trap is cool, the

next sample can be analyzed.

11.5 TERMINATION OF DATA ACQUISITION -- When all the sample components have

eluted from the GC, terminate MS data acquisition. Use appropriate data output

software to display full range mass spectra and appropriate plots of ion abundance as a

function of time. If any ion abundance exceeds the system working range, dilute the

sample aliquot in the second syringe with reagent water and analyze the diluted

aliquot.

11.6 IDENTIFICATION OF ANALYTES -- Identify a sample component by comparison of its

mass spectrum (after background subtraction) to a reference spectrum in the

user-created data base. The GC retention time of the sample component should be

within three standard deviations of the mean retention time of the compound in the

calibration mixture.

11.6.1 In general, all ions that are present above 10% relative abundance in the

mass spectrum of the standard should be present in the mass spectrum of the

sample component and should agree within absolute 20%. For example, if an

ion has a relative abundance of 30% in the standard spectrum, its abundance

in the sample spectrum should be in the range of 10 to 50%. Some ions,

particularly the molecular ion, are of special importance, and should be

evaluated even if they are below 10% relative abundance.
524.2-24

11.6.2 Identification requires expert judgment when sample components are not

resolved chromatographically and produce mass spectra containing ions

contributed by more than one analyte. When GC peaks obviously represent

more than one sample component (i.e., broadened peak with shoulder(s) or

valley between two or more maxima), appropriate analyte spectra and background spectra can be selected by examining plots of characteristic ions for

tentatively identified components. When analytes coelute (i.e., only one GC

peak is apparent), the identification criteria can be met but each analyte

spectrum will contain extraneous ions contributed by the coeluting compound. 

Because purgeable organic compounds are relatively small molecules and

produce comparatively simple mass spectra, this is not a significant problem

for most method analytes.

11.6.3 Structural isomers that produce very similar mass spectra can be explicitly

identified only if they have sufficiently different GC retention times. Acceptable resolution is achieved if the height of the valley between two peaks is less

than 25% of the average height of the two peaks. Otherwise, structural

isomers are identified as isomeric pairs. Two of the three isomeric xylenes

and two of the three dichlorobenzenes are examples of structural isomers that

may not be resolved on the capillary columns. If unresolved, these groups of

isomers must be reported as isomeric pairs.

11.6.4 Methylene chloride, acetone, carbon disulfide, and other background components appear in variable quantities in laboratory and field reagent blanks, and

generally cannot be accurately measured. Subtraction of the concentration in

the blank from the concentration in the sample is not acceptable because the

concentration of the background in the blank is highly variable.

12. DATA ANALYSIS AND CALCULATIONS

12.1 Complete chromatographic resolution is not necessary for accurate and precise

measurements of analyte concentrations if unique ions with adequate intensities are

available for quantitation. If the response for any analyte exceeds the linear range of

the calibration established in Section 10, obtain and dilute a duplicate a duplicate

sample. Do not extrapolate beyond the calibration range.

12.1.1 Calculate analyte and surrogate concentrations, using the multi-point calibration established in Section 10. Do not use the daily calibration verification

data to quantitate analytes in samples.

 (Ax)(Qis) 1000 Cx = (Ais) RF V

where: Cx = concentration of analyte or surrogate in :g/L 

 in the water sample.

Ax = integrated abundance of the quantitation ion 

 of the analyte in the sample.

Ais = integrated abundance of the quantitation ion
524.2-25

 of the internal standard in the sample.

Qis = total quantity (in micrograms) of internal

 standard added to the water sample.

V = original water sample volume in mL.

RF = mean response factor of analyte from the

 initial calibration.

12.1.2 Alternatively, use the GC/MS system software or other available proven

software to compute the concentrations of the analytes and surrogates from

the linear or second order regression curve established in Section 10. Do not

use the daily calibration verification data to quantitate analytes in samples.

12.1.3 Calculations should utilize all available digits of precision, but final reported

concentrations should be rounded to an appropriate number of significant

figures (one digit of uncertainty). Experience indicates that three significant

figures may be used for concentrations above 99 :g/L, two significant figures

for concentrations between 1- 99 :g/L, and one significant figure for lower

concentrations.

12.1.4 Calculate the total trihalomethane concentration by summing the four individual trihalomethane concentrations.

13. METHOD PERFORMANCE

13.1 Single laboratory accuracy and precision data were obtained for the method analytes

using laboratory fortified blanks with analytes at concentrations between 0.1 and 5

:g/L. Results were obtained using the four columns specified (Sect. 6.3.2.1) and the

open split or jet separator (Sect. 6.3.3.1), or the cryogenic interface (Sect. 6.3.3.2). 

These data are shown in Tables 4-8.

13.2 With these data, method detection limits were calculated using the formula (3):

MDL = S t(n-1,1-alpha = 0.99)

where:

t(n-1,1-alpha = 0.99) = Student's t value for the 99% confidence 

 level with n-1 degrees of freedom,

n = number of replicates

S = the standard deviation of the

 replicate analyses.

14. POLLUTION PREVENTION

14.1 No solvents are utilized in this method except the extremely small volumes of methanol

needed to make calibration standards. The only other chemicals used in this method
524.2-26

are the neat materials in preparing standards and sample preservatives. All are used in

extremely small amounts and pose no threat to the environment.

15. WASTE MANAGEMENT

15.1 There are no waste management issues involved with this method. Due to the nature

of this method, the discarded samples are chemically less contaminated than when

they were collected.

16. REFERENCES

1. J.W. Munch, J.W. Eichelberger, "Evaluation of 48 Compounds for Possible Inclusion in

USEPA Method 524.2, Revision 3.0: Expansion of the Method Analyte List to a Total

of 83 Compounds", J. Chro. Sci. ,30, 471,1992.

2. C. Madding, "Volatile Organic Compounds in Water by Purge and Trap Capillary

Column GC/MS," Proceedings of the Water Quality Technology Conference, American

Water Works Association, Denver, CO, December 1984.

3. J.A. Glaser, D.L. Foerst, G.D. McKee, S.A. Quave, and W.L. Budde, "Trace Analyses

for Wastewaters", Environ. Sci. Technol., 15, 1426, 1981.

4. "Carcinogens-Working with Carcinogens," Department of Health, Education, and

Welfare, Public Health Service, Center for Disease Control, National Institute for

Occupational Safety and Health, Publication No. 77-206, August 1977.

5. "OSHA Safety and Health Standards, General Industry," (29CFR1910), Occupational

Safety and Health Administration, OSHA 2206, (Revised, January 1976).

6. "Safety in Academic Chemistry Laboratories," American Chemical Society Publication,

Committee on Chemical Safety, 3rd Edition, 1979.

7. R.F. Arrendale, R.F. Severson, and O.T. Chortyk, "Open Split Interface for Capillary Gas

Chromatography/Mass Spectrometry," Anal. Chem. 1984, 56, 1533.

8. J.J. Flesch, P.S. Fair, "The Analysis of Cyanogen Chloride in Drinking Water," Proceedings of Water Quality Technology Conference, American Water Works Association, St.

Louis, MO., November 14-16, 1988.
524.2-27

17. TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA

TABLE 1. MOLECULAR WEIGHTS AND QUANTITATION IONS FOR METHOD ANALYTES

 

 Primary Secondary 

 Quantitation Quantitation

Compound MWa

 Ion Ions 

Internal standard

Fluorobenzene 96 96 77

Surrogates

4-Bromofluorobenzene 174 95 174,176

1,2-Dichlorobenzene-d4 150 152 115,150

 

Target Analytes 

Acetone 58 43 58

Acrylonitrile 53 52 53

Allyl chloride 76 76 49

Benzene 78 78 77

Bromobenzene 156 156 77,158

Bromochloromethane 128 128 49,130 

Bromodichloromethane 162 83 85,127

Bromoform 250 173 175,252

Bromomethane 94 94 96

2-Butanone 72 43 57,72

n-Butylbenzene 134 91 134

sec-Butylbenzene 134 105 134

tert-Butylbenzene 134 119 91

Carbon disulfide 76 76 --

Carbon tetrachloride 152 117 119

Chloroacetonitrile 75 48 75

Chlorobenzene 112 112 77,114

1-Chlorobutane 92 56 49

Chloroethane 64 64 66

Chloroform 118 83 85

Chloromethane 50 50 52

2-Chlorotoluene 126 91 126

4-Chlorotoluene 126 91 126

Dibromochloromethane 206 129 127

1,2-Dibromo-3-Chloropropane 234 75 155,157

1,2-Dibromoethane 186 107 109,188

Dibromomethane 172 93 95,174

1,2-Dichlorobenzene 146 146 111,148

1,3-Dichlorobenzene 146 146 111,148

1,4-Dichlorobenzene 146 146 111,148
524.2-28

TABLE 1. (continued)

 

 Primary Secondary 

 Quantitation Quantitation

Compound MWa

 Ion Ions 

trans-1,4-Dichloro-2-butene 124 53 88,75

Dichlorodifluoromethane 120 85 87

1,1-Dichloroethane 98 63 65,83

1,2-Dichloroethane 98 62 98

1,1-Dichloroethene 96 96 61,63

cis-1,2-Dichloroethene 96 96 61,98

trans-1,2-Dichloroethene 96 96 61,98

1,2-Dichloropropane 112 63 112

1,3-Dichloropropane 112 76 78

2,2-Dichloropropane 112 77 97

1,1-Dichloropropene 110 75 110,77

1,1-Dichloropropanone 126 43 83

cis-1,3-dichloropropene 110 75 110

trans-1,3-dichloropropene 110 75 110

Diethyl ether 74 59 45,73

Ethylbenzene 106 91 106

Ethyl methacrylate 114 69 99

Hexachlorobutadiene 258 225 260

Hexachloroethane 234 117 119,201

2-Hexanone 100 43 58

Isopropylbenzene 120 105 120

4-Isopropyltoluene 134 119 134,91

Methacrylonitrile 67 67 52

Methyl acrylate 86 55 85

Methylene chloride 84 84 86,49

Methyl iodide 142 142 127

Methylmethacrylate 100 69 99

4-Methyl-2-pentanone 100 43 58,85

Methyl-t-butyl ether 88 73 57

Naphthalene 128 128 --

Nitrobenzene 123 51 77

2-Nitropropane 89 46 --

Pentachloroethane 200 117 119,167

Propionitrile 55 54 --

n-Propylbenzene 120 91 120

Styrene 104 104 78

1,1,1,2-Tetrachloroethane 166 131 133,119

1,1,2,2-Tetrachloroethane 166 83 131,85

Tetrachloroethene 164 166 168,129

Tetrahydrofuran 72 71 72,42

Toluene 92 92 91

1,2,3-Trichlorobenzene 180 180 182

1,2,4-Trichlorobenzene 180 180 182

1,1,1-Trichloroethane 132 97 99,61

1,1,2-Trichloroethane 132 83 97,85
524.2-29

TABLE 1. (continued)

 

 Primary Secondary 

 Quantitation Quantitation

Compound MWa

 Ion Ions 

Trichloroethene 130 95 130,l32

Trichlorofluoromethane 136 101 103

1,2,3-Trichloropropane 146 75 77

1,2,4-Trimethylbenzene 120 105 120

1,3,5-Trimethylbenzene 120 105 120

Vinyl Chloride 62 62 64

o-Xylene 106 106 91

m-Xylene 106 106 91

p-Xylene 106 106 91

 

a

Monoisotopic molecular weight calculated from the atomic masses of the

 isotopes with the smallest masses. 
524.2-30

TABLE 2. CHROMATOGRAPHIC RETENTION TIMES FOR METHOD ANALYTES

 ON THREE COLUMNS WITH FOUR SETS OF CONDITIONSa

 

 

 Retention Time (min:sec) 

Compound Col. 1b

 Col. 2b Col. 2c Col. 3d Col. 4e

 Internal standard 

Fluorobenzene 8:49 6:27 14:06 8:03 22:00

 Surrogates

4-Bromofluorobenzene 18:38 15:43 23:38 31:21

1,2-Dichlorobenzene-d4 22:16 19:08 27:25 35:51

 Target Analytes

Acetone 16:14

Acrylonitrile 17:49

Allyl chloride 16:58

Benzene 8:14 5:40 13:30 7:25 21:32

Bromobenzene 18:57 15:52 24:00 16:25 31:52

Bromochloromethane 6:44 4:23 12:22 5:38 20:20

Bromodichloromethane 10:35 8:29 15:48 9:20 23:36

Bromoform 17:56 14:53 22:46 15:42 30:32

Bromomethane 2:01 0:58 4:48 1:17 12:26

2-Butanone 19:41

n-Butylbenzene 22:13 19:29 27:32 17:57 35:41

sec-Butylbenzene 20:47 18:05 26:08 17:28 34:04

tert-Butylbenzene 20:17 17:34 25:36 17:19 33:26

Carbon Disulfide 16:30

Carbon Tetrachloride 7:37 5:16 13:10 7:25 21:11

Chloroacetonitrile 23:51

Chlorobenzene 15:46 13:01 20:40 14:20 28:26

1-Chlorobutane 21:00

Chloroethane 2:05 1:01 1:27

Chloroform 6:24 4:48 12:36 5:33 20:27

Chloromethane 1:38 0:44 3:24 0:58 9:11

2-Chlorotoluene 19:20 16:25 24:32 16:44 32:21

4-Chlorotoluene 19:30 16:43 24:46 16:49 32:38

Cyanogen chloride (8) 1:03

Dibromochloromethane 14:23 11:51 19:12 12:48 26:57

1,2-Dibromo-3-Chloropropane 24:32 21:05 18:02 38:20

1,2-Dibromoethane 14:44 11:50 19:24 13:36 27:19

Dibromomethane 10:39 7:56 15:26 9:05 23:22

1,2-Dichlorobenzene 22:31 19:10 27:26 17:47 35:55

1,3-Dichlorobenzene 21:13 18:08 26:22 17:28 34:31

1,4-Dichlorobenzene 21:33 18:23 26:36 17:38 34:45

t-1,4-Dichloro-2-butene 31:44

Dichlorodifluoromethane 1:33 0:42 3:08 0:53 7:16

1,1-Dichloroethane 4:51 2:56 10:48 4:02 18:46
524.2-31

TABLE 2. (continued)

 

 Retention Time (min:sec) 

Compound Col. 1b

 Col. 2b Col. 2c Col. 3d Col. 4e

1,2-Dichloroethane 8:24 5:50 13:38 7:00 21:31

1,1-Dichloroethene 2:53 1:34 7:50 2:20 16:01

cis-1,2-Dichloroethene 6:11 3:54 11:56 5:04 19:53

trans-1,2-Dichloroethene 3:59 2:22 9:54 3:32 17:54

1,2-Dichloropropane 10:05 7:40 15:12 8:56 23:08

1,3-Dichloropropane 14:02 11:19 18:42 12:29 26:23

2,2-Dichloropropane 6:01 3:48 11:52 5:19 19:54

1,1-Dichloropropanone 24:52

1,1-Dichloropropene 7:49 5:17 13:06 7:10 21:08

cis-1,3-dichloropropene 11.58 16:42 24:24

trans-1,3-dichloropropene 13.46 17:54 25:33

Diethyl ether 15:31

Ethylbenzene 15:59 13:23 21:00 14:44 28:37

Ethyl Methacrylate 25:35

Hexachlorobutadiene 26:59 23:41 32:04 19:14 42:03

Hexachloroethane 36:45

Hexanone 26:23

Isopropylbenzene 18:04 15:28 23:18 16:25 30:52

4-Isopropyltoluene 21:12 18:31 26:30 17:38 34:27

Methacrylonitrile 20:15

Methylacrylate 20:02

Methylene Chloride 3:36 2:04 9:16 2:40 17:18

Methyl Iodide 16:21

Methylmethacrylate 23:08

4-Methyl-2-pentanone 24:38

Methyl-t-butyl ether 17:56

Naphthalene 27:10 23:31 32:12 19:04 42:29

Nitrobenzene 39:02

2-Nitropropane 23:58

Pentachloroethane 33:33

Propionitrile 19:58

n-Propylbenzene 19:04 16:25 24:20 16:49 32:00

Styrene 17:19 14:36 22:24 15:47 29:57

1,1,1,2-Tetrachloroethane 15:56 13:20 20:52 14:44 28:35

1,1,2,2-Tetrachloroethane 18:43 16:21 24:04 15:47 31:35

Tetrachloroethene 13:44 11:09 18:36 13:12 26:27

Tetrahydrofuran 20:26

Toluene 12:26 10:00 17:24 11:31 25:13

1,2,3-Trichlorobenzene 27:47 24:11 32:58 19:14 43:31

1,2,4-Trichlorobenzene 26:33 23:05 31:30 18:50 41:26

1,1,1-Trichloroethane 7:16 4:50 12:50 6:46 20:51

1,1,2-Trichloroethane 13:25 11:03 18:18 11:59 25:59

Trichloroethene 9:35 7:16 14:48 9:01 22:42

Trichlorofluoromethane 2:16 1:11 6:12 1:46 14:18

1,2,3-Trichloropropane 19:01 16:14 24:08 16:16 31:47

1,2,4-Trimethylbenzene 20:20 17:42 31:30 17:19 33:33
524.2-32

TABLE 2. (continued)

 

 Retention Time (min:sec) 

Compound Col. 1b

 Col. 2b Col. 2c Col. 3d Col. 4e

1,3,5-Trimethylbenzene 19:28 16:54 24:50 16:59 32:26

Vinyl chloride 1:43 0:47 3:56 1:02 10:22

o-Xylene 17:07 14:31 22:16 15:47 29:56

m-Xylene 16:10 13:41 21:22 15:18 28:53

p-Xylene 16:07 13:41 21:18 15:18 28:53

 

a

Columns 1-4 are those given in Sect. 6.3.2.1; retention times were measured

 from the beginning of thermal desorption from the trap (columns 1-2, and 4) or

 from the beginning of thermal release from the cryogenic interface (column 3).

b

GC conditions given in Sect. 11.3.1.

c

GC conditions given in Sect. 11.3.2.

d

GC conditions given in Sect. 11.3.3.

e

GC conditions given in Sect. 11.3.4.
524.2-33

 TABLE 3. ION ABUNDANCE CRITERIA FOR 4-BROMOFLUOROBENZENE (BFB) 

 

 Mass

 (M/z) Relative Abundance Criteria 

 50 15 to 40% of mass 95

 75 30 to 80% of mass 95

 95 Base Peak, 100% Relative Abundance

 96 5 to 9% of mass 95

173 < 2% of mass 174

174 > 50% of mass 95

175 5 to 9% of mass 174

176 > 95% but < 101% of mass 174

177 5 to 9% of mass 176

 
524.2-34

TABLE 4. ACCURACY AND PRECISION DATA FROM 16-31 DETERMINATIONS OF 

 THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE 

 CAPILLARY COLUMN 1a

Compound

True

Conc.

Range

(:g/L)

Mean

Accuracy

(% of True

Value)

Rel.

Std.

Dev.

(%)

Method

Det.

Limitb

(:g/L)

Benzene

Bromobenzene

Bromochloromethane

Bromodichloromethane

Bromoform

Bromomethane

n-Butylbenzene

sec-Butylbenzene

tert-Butylbenzene

Carbon Tetrachloride

Chlorobenzene

Chloroethane

Chloroform

Chloromethane

2-Chlorotoluene

4-Chlorotoluene

Dibromochloromethane

1,2-Dibromo-3-Chloropropane

1,2-Dibromoethane

Dibromomethane

1,2-Dichlorobenzene

1,3-Dichlorobenzene

1,4-Dichlorobenzene

Dichlorodifluoromethane

1,1-Dichloroethane

1,2-Dichloroethane

1,1-Dichloroethene

cis-1,2-Dichloroethene

trans-1,2-Dichloroethene

1,2-Dichloropropane

1,3-Dichloropropane

2,2-Dichloropropane

1,1-Dichloropropene

cis-1,2-Dichloropropene

trans-1,2-Dichloropropene

Ethylbenzene

Hexachlorobutadiene

Isopropylbenzene

4-Isopropyltoluene

0.1-10

0.1-10

0.5-10

0.1-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.1-10

0.5-10

0.5-10

0.5-10

0.1-10

0.1-10

0.1-10

0.5-10

0.5-10

0.5-10

0.1-10

0.5-10

0.2-20

0.5-10

0.5-10

0.1-10

0.1-10

0.5-10

0.1-10

0.1-10

0.1-10

0.5-10

0.5-10

0.1-10

0.5-10

0.5-10

0.1-10

97

100

90

95

101

95

100

100

102

84

98

89

90

93

90

99

92

83

102

100

93

99

103

90

96

95

94

101

93

97

96

86

98

99

100

101

99

5.7

5.5

6.4

6.1

6.3

8.2

7.6

7.6

7.3

8.8

5.9

9.0

6.1

8.9

6.2

8.3

7.0

19.9

3.9

5.6

6.2

6.9

6.4

7.7

5.3

5.4

6.7

6.7

5.6

6.1

6.0

16.9

8.9

8.6

6.8

7.6

6.7

0.04

0.03

0.04

0.08

0.12

0.11

0.11

0.13

0.14

0.21

0.04

0.10

0.03

0.13

0.04

0.06

0.05

0.26

0.06

0.24

0.03

0.12

0.03

0.10

0.04

0.06

0.12

0.12

0.06

0.04

0.04

0.35

0.10

0.06

0.11

0.15

0.12
TABLE 4. ACCURACY AND PRECISION DATA FROM 16-31 DETERMINATIONS OF 

 THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE 

 CAPILLARY COLUMN 1a

Compound

True

Conc.

Range

(:g/L)

Mean

Accuracy

(% of True

Value)

Rel.

Std.

Dev.

(%)

Method

Det.

Limitb

(:g/L)

524.2-35

Methylene Chloride

Naphthalene

n-Propylbenzene

Styrene

1,1,1,2-Tetrachloroethane

1,1,2,2-Tetrachloroethane

Tetrachloroethene

Toluene

1,2,3-Trichlorobenzene

1,2,4-Trichlorobenzene

1,1,1-Trichloroethane

1,1,2-Trichloroethane

Trichloroethene

Trichlorofluoromethane

1,2,3-Trichloropropane

1,2,4-Trimethylbenzene

1,3,5-Trimethylbenzene

Vinyl Chloride

o-Xylene

m-Xylene

p-Xylene

0.1-10

0.1-100

0.1-10

0.1-100

0.5-10

0.1-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.5-10

0.1-31

0.1-10

0.5-10

95

104

100

102

90

91

89

102

109

108

98

104

90

89

108

99

92

98

103

97

104

5.3

8.2

5.8

7.2

6.8

6.3

6.8

8.0

8.6

8.3

8.1

7.3

7.3

8.1

14.4

8.1

7.4

6.7

7.2

6.5

7.7

0.03

0.04

0.04

0.04

0.05

0.04

0.14

0.11

0.03

0.04

0.08

0.10

0.19

0.08

0.32

0.13

0.05

0.17

0.11

0.05

0.13

a

Data obtained by using Column 1 with a jet separator interface and a quadrupole mass

spectrometer (Section 11.3.1) with analytes divided among three solutions.

b

Replicate samples at the lowest concentration listed in Column 2 of this table were

analyzed. These results were used to calculate MDLs.
524.2-36

TABLE 5. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF 

 THE METHOD ANALYTES IN REAGENT WATER USING THE CRYOGENIC 

 TRAPPING OPTION AND A NARROW-BORE CAPILLARY COLUMN 3a

Compound

True

Conc.

(:g/L)

Mean

Accuracy

(% of True

Value)

Rel.

Std.

Dev.

(%)

Method

Det.

Limit

(:g/L)

Benzene

Bromobenzene

Bromochloromethane

Bromodichloromethane

Bromoform

Bromomethane

n-Butylbenzene

sec-Butylbenzene

tert-Butylbenzene

Carbon Tetrachloride

Chlorobenzene

Chloroethane

Chloroform

Chloromethane

2-Chlorotoluene

4-Chlorotoluene

Cyanogen Chlorideb

Dibromochloromethane

1,2-Dibromo-3-Chloropropane

1,2-Dibromoethane

Dibromomethane

1,2-Dichlorobenzene

1,3-Dichlorobenzene

1,4-Dichlorobenzene

Dichlorodifluoromethane

1,1-Dichloroethane

1,2-Dichloroethane

1,1-Dichloroethene

cis-1,2-Dichloroethene

trans-1,2-Dichloroethene

1,2-Dichloropropane

1,3-Dichloropropane

2,2-Dichloropropane

1,1-Dichloropropene

cis-1,2-Dichloropropene

trans-1,2-Dichloropropene

Ethylbenzene

Hexachlorobutadiene

0.1

0.5

0.5

0.1

0.1

0.1

0.5

0.5

0.5

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

99

97

97

100

99

99

94

90

90

92

91

100

95

99

99

96

92

99

92

97

93

97

99

93

99

98

100

95

100

98

96

99

99

98

99

100

6.2

7.4

5.8

4.6

5.4

7.1

6.0

7.1

2.5

6.8

5.8

5.8

3.2

4.7

4.6

7.0

10.6

5.6

10.0

5.6

6.9

3.5

6.0

5.7

8.8

6.2

6.3

9.0

3.7

7.2

6.0

5.8

4.9

7.4

5.2

6.7

0.03

0.11

0.07

0.03

0.20

0.06

0.03

0.12

0.33

0.08

0.03

0.02

0.02

0.05

0.05

0.05

0.30

0.07

0.05

0.02

0.03

0.05

0.05

0.04

0.11

0.03

0.02

0.05

0.06

0.03

0.02

0.04

0.05

0.02

0.03

0.04
TABLE 5. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF 

 THE METHOD ANALYTES IN REAGENT WATER USING THE CRYOGENIC 

 TRAPPING OPTION AND A NARROW-BORE CAPILLARY COLUMN 3a

Compound

True

Conc.

(:g/L)

Mean

Accuracy

(% of True

Value)

Rel.

Std.

Dev.

(%)

Method

Det.

Limit

(:g/L)

524.2-37

Isopropylbenzene

4-Isopropyltoluene

Methylene Chloride

Naphthalene

n-Propylbenzene

Styrene

1,1,1,2-Tetrachloroethane

1,1,2,2-Tetrachloroethane

Tetrachloroethene

Toluene

1,2,3-Trichlorobenzene

1,2,4-Trichlorobenzene

1,1,1-Trichloroethane

1,1,2-Trichloroethane

Trichloroethene

Trichlorofluoromethane

1,2,3-Trichloropropane

1,2,4-Trimethylbenzene

1,3,5-Trimethylbenzene

Vinyl Chloride

o-Xylene

m-Xylene

p-Xylene

0.5

0.5

0.5

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

98

87

97

98

99

96

100

100

96

100

98

91

100

98

96

97

96

96

99

96

94

94

97

6.4

13.0

13.0

7.2

6.6

19.0

4.7

12.0

5.0

5.9

8.9

16.0

4.0

4.9

2.0

4.6

6.5

6.5

4.2

0.2

7.5

4.6

6.1

0.10

0.26

0.09

0.04

0.06

0.06

0.04

0.20

0.05

0.08

0.04

0.20

0.04

0.03

0.02

0.07

0.03

0.04

0.02

0.04

0.06

0.03

0.06

a

Data obtained by using Column 3 with a cryogenic interface and a quadrupole mass

spectrometer (Section 11.3.3).

b

Reference 8.
524.2-38

TABLE 6. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF 

 THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE 

 CAPILLARY COLUMN 2a

Compound No.b

Mean Accuracy (% of

True Value,

2 :g/L

Conc.)

RSD

(%)

Mean Accuracy

(% of True

Value,

0.2 :g/L

Conc.)

RSD

(%)

Internal Standard

Fluorobenzene

Surrogates

4-Bromofluorobenze

1,2-Dichlorobenzene-d4

Target Analytes

Benzene

Bromobenzene

Bromochloromethane

Bromodichloromethane

Bromoform

Bromomethane

n-Butylbenzene

sec-Butylbenzene

tert-Butylbenzene

Carbon Tetrachloride

Chlorobenzene

Chloroethanec

Chloroform

Chloromethane

2-Chlorotoluene

4-Chlorotoluene

Dibromochloromethane

1,2-Dibromo-3-Chloropropanec

1,2-Dibromoethanec

Dibromomethane

1,2-Dichlorobenzene

1,3-Dichlorobenzene

1,4-Dichlorobenzene

Dichlorodifluoromethane

1,1-Dichloroethane

1,2-Dichloroethane

1

2

3

37

38

4

5

6

7

39

40

41

8

42

9

10

43

44

11

13

45

46

47

14

15

16

ñ

98

97

97

102

99

96

89

55

89

102

101

84

104

97

110

91

89

95

99

93

100

98

38

97

102

ñ

1.8

3.2

4.4

3.0

5.2

1.8

2.4

27.

4.8

3.5

4.5

3.2

3.1

2.0

5.0

2.4

2.0

2.7

2.1

2.7

4.0

4.1

25.

2.3

3.8

ñ

96

95

113

101

102

100

90

52

87

100

100

92

103

95

d

 

108

108

100

95

94

87

94

d

 

85

100

ñ

1.3

1.7

1.8

1.9

2.9

1.8

2.2

6.7

2.3

2.8

2.9

2.6

1.6

2.1

3.1

4.4

3.0

2.2

5.1

2.3

2.8

3.6

2.1
TABLE 6. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF 

 THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE 

 CAPILLARY COLUMN 2a

Compound No.b

Mean Accuracy (% of

True Value,

2 :g/L

Conc.)

RSD

(%)

Mean Accuracy

(% of True

Value,

0.2 :g/L

Conc.)

RSD

(%)

524.2-39

1,1-Dichloroethene

cis-1,2-Dichloroethene

trans-1,2-Dichloroethene

1,2-Dichloropropane

1,3-Dichloropropane

2,2-Dichloropropanec

1,1-Dichloropropenec

cis-1,2-Dichloropropenec

trans-1,2-Dichloropropene

Ethylbenzene

Hexachlorobutadiene

Isopropylbenzene

4-Isopropyltoluene

Methylene Chloride

Naphthalene

n-Propylbenzene

Styrene

1,1,1,2-Tetrachloroethane

1,1,2,2-Tetrachloroethane

Tetrachloroethene

Toluene

1,2,3-Trichlorobenzene

1,2,4-Trichlorobenzene

1,1,1-Trichloroethane

1,1,2-Trichloroethane

Trichloroethene

Trichlorofluoromethane

1,2,3-Trichloropropane

1,2,4-Trimethylbenzene

1,3,5-Trimethylbenzene

Vinyl Chloride

17

18

19

20

21

25

48

26

49

50

27

51

52

53

28

29

30

54

55

56

31

32

33

34

35

57

58

36

90

100

92

102

92

96

96

91

103

95

 e

 

93

102

95

99

101

97

105

90

92

94

107

99

81

97

93

88

104

2.2

3.4

2.1

2.2

3.7

1.7

9.1

5.3

3.2

3.6

7.6

4.9

4.4

2.7

4.6

4.5

2.8

5.7

5.2

3.9

3.4

2.9

4.6

3.9

3.1

2.4

3.5

87

89

85

103

93

99

100

88

101

95

e

 

78

97

104

95

84

92

126

78

83

94

109

106

48

91

106

97

115

3.8

2.9

2.3

2.9

3.2

2.1

4.0

2.4

2.1

3.1

8.3

2.1

3.1

3.8

3.6

3.3

1.7

2.9

5.9

2.5

2.8

2.5

13.

2.8

2.2

3.2

14.
TABLE 6. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF 

 THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE 

 CAPILLARY COLUMN 2a

Compound No.b

Mean Accuracy (% of

True Value,

2 :g/L

Conc.)

RSD

(%)

Mean Accuracy

(% of True

Value,

0.2 :g/L

Conc.)

RSD

(%)

524.2-40

o-Xylene

m-Xylene

p-Xylene

59

60

61

97

f

 

98

1.8

2.3

98

f

 

103

1.7

1.4

a

Data obtained using Column 2 with the open split interface and an ion trap mass spectrometer (Section 11.3.2) with all method analytes in the same reagent water solution.

b

Designation in Figures 1 and 2.

c

Not measured; authentic standards were not available.

d

Not found at 0.2 :g/L. e

Not measured; methylene chloride was in the laboratory reagent blank.

f

m-xylene coelutes with and cannot be distinguished from its isomer p-xylene, No 61.
524.2-41

TABLE 7. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF 

 METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE CAPILLARY 

 COLUMN 4a

Compound

True

Conc.

(:g/L)

Mean

Conc.

Detected

(:g/L)

Rel.

Std.

Dev.

(%)

Method

Detect.

Limit

(:g/L)

Acetone

Acrylonitrile

Allyl Chloride

2-Butanone

Carbon Disulfide

Chloroacetonitrile

1-Chlorobutane

trans-Dichloro-2-Butene

1,1-Dichloropropanone

cis-1,3-Dichloropropene

trans-1,3-Dichloropropene

Diethyl Ether

Ethyl Methacrylate

Hexachloroethane

2-Hexanone

Methacrylonitrile

Methylacrylate

Methyl Iodide

Methylmethacrylate

4-Methyl-2-Pentanone

Methyl-tert-Butylether

Nitrobenzene

2-Nitrobenzene

Pentachloroethane

Propionitrile

Tetrahydrofuran

1.0

1.0

1.0

2.0

0.20

1.0

1.0

1.0

5.0

0.20

0.10

1.0

0.20

0.20

1.0

1.0

1.0

0.20

1.0

0.40

0.40

2.0

1.0

0.20

1.0

5.0

1.6

0.81

0.90

2.7

0.19

0.83

0.87

1.3

4.2

0.20

0.11

0.92

0.23

0.18

1.1

0.92

1.2

0.19

1.0

0.56

0.52

2.1

0.83

0.23

0.87

3.9

5.7

8.7

4.7

5.6

15

4.7

6.6

8.7

7.7

3.1

14

9.5

3.9

10

12

4.2

12

3.1

13

9.7

5.6

18

6.2

20

5.3

13

0.28

0.22

0.13

0.48

0.093

0.12

0.18

0.36

1.0

0.020

0.048

0.28

0.028

0.057

0.39

0.12

0.45

0.019

0.43

0.17

0.090

1.2

0.16

0.14

0.14

1.6

a

Data obtained using Column 4 with the open split interface and an ion trap mass spectrometer.
524.2-42

TABLE 8. ACCURACY AND PRECISION FROM FOUR DETERMINATIONS OF METHOD ANALYTES IN THREE WATER MATRICES

FORTIFIED AT 20 :G/La

REAGENT WATER RAW WATER TAP WATER

Compound

Mean

(:g/L)

Dev.

(%)

(% of True

Value)

Mean

:( g/L)

Dev.

(%)

(% of True

Value)

Mean

:( g/L)

Dev.

(%)

(% of True

Value)

AcetoneAcrylonitrileAllyl Chloride2-ButanoneCarbon DisulfideChloroacetonitrile1-Chlorobutanet-1,2-Dichloro-2-Butene1,1-DichloropropanoneDiethyl EtherEthyl MethacrylateHexachloroethane2-HexanoneMethacrylonitrileMethylacrylate

192020171920181920182020192020

 12%

4.7%5.1%

 11%

6.4%4.1%6.4%4.1%5.6%6.7%3.7%6.1%6.3%3.4%3.7%

95%

100%100%

85%95%

100%

90%95%

100%

90%

100%100%

95%

100%100%

212220191823192222222321212322

3.7%3.4%2.8%7.3%2.5%4.7%2.2%2.9%6.4%3.4%2.6%2.5%3.8%2.9%3.1%

105%110%100%

95%90%

115%

95%

110%110%110%115%105%105%115%110%

222119171823172121222221212221

8.2%1.3%3.5%5.6%3.0%1.3%2.2%0.90%7.7%2.6%1.8%2.0%4.0%2.0%2.1%

110%105%

95%85%90%

115%

85%

105%105%110%110%105%105%110%105%
524.2-43

TABLE 8. ACCURACY AND PRECISION FROM FOUR DETERMINATIONS OF METHOD ANALYTES IN THREE WATER

MATRICES FORTIFIED AT 20 :G/La

Reagent Water Raw Water Tap Water

Compound

Mean

(:g/L)

Dev.

(%)

(% of True

Value)

Mean

(:g/L)

Dev.

(%)

(% of True

Value)

Mean

(:g/L)

Dev.

(%)

(% of True

Value)

Methyl IodideMethylmethacrylate4-Methyl-2-PentanoneMethyl-tert-ButyletherNitrobenzene2-NitropropanePentachloroethanePropionitrileTetrahydrofuran

202019192020192020

4.4%3.7%8.7%3.5%5.4%6.1%5.2%4.5%2.8%

100%100%

95%95%

100%100%

95%

100%100%

192321222223212324

3.8%3.3%5.5%2.5%4.8%5.1%2.6%3.9%3.2%

95%

115%105%110%110%115%105%115%120%

192322222122222321

3.0%2.7%7.2%3.6%2.4%3.2%1.7%2.4%2.9%

95%

115%110%110%105%110%110%115%105%

aData obtained using Column 4 with the open-split interface and an ion trap mass spectrometer with all Table 8 analyses in the same

reagent water solution (1).
524.2-44
524.2-45
524.2-46
524.2-47